Title says it all.
OS X 10.9.5, relatively new install, 2 weeks old
AE CC 13.0.0.214
Late 2013 MacPro
CMD+Shift+"C" no longer pre-composes until I reboot the system, will work for a period of time, and then stop.
Kind of annoying, since I can't remember the last time I actually used the mouse to pre-compose something before today.